Add pasta to boiling water and cook according to package directions, until al dente (tender yet still firm to the bite). Drain pasta, reserving 1 cup of the cooking water.

Add hot spaghetti to bacon mixture in skillet and toss well over medium-low heat until pasta is coated. Add egg mixture and a little of the cooking water; toss gently until spaghetti looks creamy. Add cheese and toss to combine. Serve immediately.